The invention relates to a self-healing electrical capacitor, in particular for AC, consisting of coiled layers of polypropylene films with metallizations, whereby the metallizations are applied onto the films in such a way that exposed margins are left at the longitudinal sides of the films.
Such capacitors are known in the art. The prior art capacitors generally have capacitance values which decrease with increasing operational duration. This is due to the fact that the metallization is destroyed in the region adjacent to the exposed margins, due to the increased marginal field strength. The marginal field strength F.sub.K is thereby defined as follows: EQU F.sub.K .about. F.sub.H .sqroot.d.sub.1 /d.sub.2,
whereby d.sub.1 is the thickness of the dielectric, and d.sub.2 the thickness of the metal coating at the margin; F.sub.H is the field strength of the homogeneous field in the inner portion of the capacitor. The marginal field strength is 10 to 100 times higher than the homogeneous field strength in the inner portions of the capacitor.